Acute Encephalopathy Associated with Influenza A Virus Infection

Abstract

Twenty-one patients aged 4-78 years with influenza A virus-associated acute encephalopathy were studied. Influenza A virus could be detected only in a cerebrospinal fluid (CSF) specimen obtained from 1 of 18 patients, despite the use of a highly sensitive polymerase chain reaction assay. Six patients experienced influenzal encephalopathy during the course of respiratory illness. Five of these patients had hypoprothrombinemia and 4 had increased serum creatinine levels, indicating hepatic and/or renal dysfunction. Fourteen patients experienced postinfluenzal encephalopathy <or=3 weeks after resolution of acute respiratory symptoms. In 6 patients, focal areas of high signal intensity were visible on T2-weighted magnetic resonance images of the brain. Adenovirus DNA was detected in CSF specimens obtained from 4 (36%) of 11 patients with postinfluenzal encephalopathy. Thus, influenzal encephalopathy is frequently associated with metabolic disorders, whereas postinfluenzal encephalopathy appears to have different possible etiologies.

Acute Encephalopathy Associated with Influenza A Infection in Adults

“…High CSF and blood cytokine/chemokine (CXCL8/IL-8, CCL2/ MCP-1, IL-6, CXCL10/IP-10) levels were detected. No ev- (1,6). Findings are consistent with previous reports on adult cases of influenza-associated encephalopathy: patients are all unvaccinated, pleocytosis and cerebral imaging abnormalities (even with magnetic resonance imaging) are usually absent, and symptoms are generally self-limiting (1,6).…”

Neurologic Complications Associated With Influenza A in Children During the 2003–2004 Influenza Season in Houston, Texas

“…12 With the advent of serologic testing, confirmed cases of influenza virus infection (A and B) have been associated with seizures (febrile and nonfebrile), 6,13,14 alterations in mental status ranging from confusion and lethargy to coma, 7,8,15,16 acute inflammatory demyelinating polyneuropathy (Guillain-Barre syndrome), 17,18 acute disseminated encephalomyelitis, 17 transverse myelitis, 17 abnormal movements, 19 acute psychosis, 20 frontal lobe syndromes, 21 mutism, 9,10 and visual hallucinations. 22 These complications have been reported sporadically in the literature over the past 60 years.…”

“…6,21,[23][24][25] In these series, a subset of patients (both children and adults) developed a newly described entity termed "acute necrotizing encephalopathy" (ANE). 14,23,26,27 Many patients with this syndrome present with high fever, seizures, and alterations in mental status that rapidly progress to coma. Brain imaging often demonstrates symmetric white matter, thalamic, basal ganglia, and/or pontine involvement.…”

“…All of the patients also had clinical symptoms and signs of influenza. The timing and concurrent influenzal symptoms suggest that acute influenza caused by the influenza A virus, rather than a "postinfluenza encephalopathy," 14,16 was responsible for the associated neurologic findings.…”

“…Recently, RT-PCR techniques have been used to test for the presence of viral RNA in serum and CSF samples; however, these techniques have met with varied success, and the majority of studies have been unable to provide direct evidence of influenza virus infection in CNS sites. 10,14 RT-PCR for influenza A viral RNA was not done on any of the CSF samples in this case series because priority was given to viral culture techniques, leaving insufficient quantities for PCR.…”